"The global financial crisis is most immediate; the more existential is climate change. The urgency of the first is no excuse for neglecting the second. To the contrary, it is an opportunity to kill two birds with one stone," says a joint op-ed piece written by UN Secretary-General Ban Ki-moon, Indonesian President Susilo Bambang Yudhoyono, Polish Prime Minister Donald Tusk and Danish Prime Minister Anders Fogh Rasmussen.

Indonesia's Bali was the venue of last year's conference on climate change, while Poland is hosting further negotiations in Poznan in December and Denmark will host talks next year to draw up a successor agreement to the Kyoto Protocol on reducing greenhouse gases, which expires in 2012.

In the op-ed, published in 'The International Herald Tribune', the four leaders stressed that a "green economy" is the answer to both the financial crisis and climate change, since the fastest growing industry in the world at present is renewable energy.

That's where jobs of the future are already being created, and where much of the technological innovation is taking place that will usher in our next era of economic transformation, the leaders wrote.

The UN Environment Programme estimates that global investment in zero-greenhouse energy will reach USD 1.9 trillion by 2020 a significant portion of the global GDP. Worldwide, nearly two million people are employed in the new wind and solar power industries -- half of them in China alone.